It is the time, not the ratio.
Droogh
Joep M
JM
Dijkema
L Marjon
LM
Ligtenberg
Jack J M
JJ
Tulleken
Jaap E
JE
Zijlstra
Jan G
JG
D006801:Humans; D012121:Respiration, Artificial; D012143:Respiratory Physiological Phenomena; D013997:Time Factors